The invention relates to the field of material spreaders for trucks and provides an apparatus for selectively distributing sand, salt, gravel, asphalt or like material either rearwardly of a truck, laterally of the truck, or both, making it possible to simultaneously service or treat two or more lanes of a roadway with a single pass by the truck.
Dump trucks have long been used for the repair and maintenance of roads and highways. Typically, the trucks are used everywhere for carrying and dropping materials such as sand, gravel, and asphalt for the repair and maintenance of roads. In colder climates the trucks are used extensively to distribute salt, sand and other chemicals to alleviate otherwise slippery and hazardous road conditions. A variety of material spreaders has been conceived and used to distribute materials from the trucks. Typically, the spreader is mounted at the rear of the truck bin and pivots relative to the bin just as a standard dump truck tailgate would pivot. It usually includes equipment to break down clods of the material and also some dispensing means for dropping a measured amount of material directly rearwardly and downwardly from the truck and onto the roadway. Such spreaders are widely used and generally effective for distributing material directly rearwardly from the truck when only the lane immediately behind the truck is to be treated and is to receive material. Such spreaders are ineffective for distributing material laterally from the truck in order to treat a traffic lane adjacent to the lane in which the truck is traveling.
To meet the need to spread material laterally from the truck as well as rearwardly, trucks were provided with a spinning radial type spreader, and such spinners are effective to broadcast material in a 360.degree. radius centered on the spinner. While the spinner is a useful device, it does have limitations. For example, the spinner discharges material in a 360.degree. radius, and accordingly does not permit material to be directed to specific areas of the roadway. For example, if it is desired to sand, salt or otherwise treat the lane in which the truck is traveling and also the left, oncoming traffic lane while the truck travels in its regular right lane, the spinner would waste a substantial amount of material in that it would spread material over the two described lanes and also distribute it to the right of the truck and onto the right shoulder and roadside area where it is unneeded. In addition, the rapid rotational action of the spinner often discharges material at a relatively high velocity and can cause damage to adjacent vehicles.
In recent years conveyors have been mounted behind the dump truck to receive material dropped from the bin and to move the material laterally to right or left, permitting the material to be dispensed in the lane to the left of that in which the truck is traveling, or alternatively in the lane immediately to the right of the lane in which the truck is traveling. Such a conveyor also makes it possible for the truck to fill washouts or potholes in the road or adjacent the road by using the conveyor to move the material directly to the hole and drop it into the pothole or washout. However, mounting of the conveyor behind and below the truck bin resulted in all material from the bin being intercepted by the conveyor, and it was no longer possible to drop material directly rearwardly from the bin and onto the roadway or to sand or salt the roadway directly behind the truck without first going through the inconvenience of removing the conveyor from the truck. Accordingly, it would be advantageous to be able to utilize the desirable aspects of the basic dispensing means to thereby drop the material directly downwardly and rearwardly of the truck as well as simultaneously utilize the advantages of a conveyor system for laterally moving material to left or right of the truck. The present invention permits such a combination and allows simultaneous rearward or lateral dispensing of material from the truck.
Another problem encountered by known material spreaders utilizing conveyors is that ice, snow, mud, slush and the like are churned upwardly and rearwardly from the wheels of the truck and tend to reach the conveyor, sometimes reducing its efficiency. The present invention includes a splash panel structure which intercepts snow, ice, mud and the like and prevents its reaching the conveyor.